Underwater transducer configuration



March 26, 1958 R. M. BRIDGES ETAL 3,

UNDERWATER TRANSDUCER CONFIGURAT ION Filed Nov. 3, 1966 United StatesPatent Ofiice 3,375,488 Patented Mar. 26, 1968 3,375,488 UNDERWATERTRANSDUCER CONFIGURATION Robert M. Bridges, Northridge, and WilburNerenstein,

North Hollywood, Calif., assignors to The Bendix Corporation, acorporation of Delaware Filed Nov. 3, 1966, Ser. No. 591,830 8 Claims.(Cl. 340-8) ABSTRACT OF THE DISCLOSURE An underwater transducerconfigured for high speed descent into the water and ascent out of thewater having an elongated cylindrical body with fins at its lower end,

This invention relates to underwater transducer equipment, and morespecifically to a transducer having unusually good hydrodynamicproperties.

In some applications involving underwater mapping or searching, apremium is placed on being able to cover a substantial area in a minimumof time. In such operations it is conventional for the transducers usedto be lowered at the end of a cable and retrieved by Winding in thecable by means of a hoist mechanism. Where it is necessary to operate atconsiderable depths, it is apparent that an appreciable amount of timemust be involved in the lowering and raising operation. The timeinvolved in getting the transducer to the operating depth and inreturning it to the accompanying seaborne or airborne vehicle may begreatly in excess of the time the transducer is in operating position.Thus the rate of descent and ascent of the transducer has a very directbearing on the number of locations to which it may be moved in a givenperiod of time and, therefore, upon the area which it may cover.

In order to extend this area substantially, the applicants herein havedevised a transducer having uniquely good hydrodynamic properties suchthat it descends rapidly and substantially vertically into the water,ascends rapidly and vertically out of the water, and yet has acousticperformance at least equivalent to conventional transducers which haverelatively poor hydrodynamic qualities. It is, therefore, an object ofthe present invention to provide a transducer configuration foroperation at great depths which will descend substantially verticallyand much more rapidly into the water than transducers presently in use.

It is another object of the present invention to provide a transducerconfiguration which may be pulled substantially vertically out of thewater from considerable depths much more rapidly than transducerspresently in use.

It is another object of the present invention to provide a transducerconfiguration which accomplishes the above objectives and which may bedropped into the water or pulled out of the water by means of a cablewith a minimum of turbulence from non-axial movement or hydrodynamicdrag.

It is a further object of the present invention to provide a transducerconfiguration which accomplishes the above objectives and which is ofsuch configuration that a minimum of interference in the operation ofthe receiving transducer elements is caused when said transmittingelements are energized.

Other objects and advantages will become apparent from the followingspecification taken in connection with the accompanying drawings inwhich:

FIGURE 1 is an elevation, partially in section, of a transducerconfiguration according to my invention;

FIGURE 2 is a section taken on line 2-2 of FIG- URE 1; v

FIGURE 3 is an enlarged view of a portion of FIG- URE 1 shown insection; and

FIGURE 4 is an enlarged view of another portion of FIGURE 1 shown insection.

Referring now to FIGURE 1, the transducer 'body 10 is an elongated,generally cylindrical member with rounded or ogival ends to provide astreamlined contour for passage through the water in either direction.At the upper end is shown a cable 12 which is attached to a hoistmechanism (not shown) carried on the accompanying water-borne or airvehicle. The hoist mechanism, which forms no part of the presentinvention, may be any of several types known in the art. Attached to theupper end of the body 10 by means of a plurality of radially extendingsupport members or struts 14 is a drum-shaped member 16- of considerablygreater diameter than body 10 which serves as a housing for thereceiving or listening transducer elements. The transducer elements 18are arranged in groups longitudinally and retained in retainer members17 such that each group operates as a single unit or stave. A number ofsuch staves are positioned around the periphery of member 16 facingoutwardly so that they will respond to acoustic energy reaching themfrom the surrounding water. Each stave responds as the acoustic energyreaches it, converting the acoustical signal into an electrical signalwhich is processed to form an output pattern which is normally displayedon the face of a cathode ray tube in the accompanying vehicle. Passages19 are incorporated in struts 14 to accommodate the wiring from thestaves to the interior of body 10.

An electronic package for processing the transducer signals is locatednear the central and upper parts of the body 10, such as within theinterior of section 20. Positioned below the electronic package is anaxially arranged array of ring-shaped transmitting transducer elements22 which may be of piezoelectric material and which are separated bymeans of spacer members 24 which may be of rubber or any elastomerhaving the desired properties for operation at substantial depths andwhich are contained within a rubber sheath 26. The spacers 24 and sheath26 are essentially transparent to acoustic signals but serve to retainwithin the interior of the sheath 26 an essentially noncompressibleliquid such as kerosene so that the pressures may be equalized acrossthe transducer elements. Passing through the center of the transducerelements is a center post 28 which is typically used in combination witha threaded member (not shown) to compress the transducer elements 22 andthe spacers 24 together in axial alignment and which may also serve asan t acoustic loading member for-tuning the transmitting trans ducer.Tuning may be accomplished by varying the diameter of post 28: thelarger the diameter, the smaller the space between itself and the insideof the transducer ele ments 22 and the higher the mechanical resonantfre quency of the assembly.

The lower or nose section 39, aside from being ogival or streamlined inconfiguration to minimize resistance through the Water, should besymmetric-a1 such that it does not cause the transduce'r'to steer awayfrom as near ly vertical a descent as possible. A plurality of fins 32are attached to nose section 30 to inhibit nutation or non-axialmovement of body on ascent. Since success ful operation of the entireassembly depends upon the center of gravity being substantially belowthe center of the body 10, extra weight may be added by making sec tion30 as heavy as required' to assure a proper location for the center ofgravity. In general, the entire assembly should be made as dense aspossible compatible with the desired location of the center of gravityto assure a swift and straight descent. Both because of the highhydrostatic pressures encountered and because of the need for maximumdensity, voids in the electronic package should be eliminated.

With the structure shown, the behavior of the transducer during descentis straight and essentially vertical, and its characteristics are muchlike those of an arrow. The cross-section of struts 14 and the receivingtransducer sup ort 16 should be such as to make the resistance tomovement through the water in both directions as small as possible, butthe support 16 does provide the necessary resistance to keep itself onthe trailing or upper end of the assembly on descent. This orientationis further main tained by having the center of gravity of the assemblyas low as possible and at least substantially below the center of thebody 10. The substantially vertical orientation is maintained when thetransducer is stationary in operating position due to its high densityand relatively small cross-sectional area which gives it substantialresistance to tipping from the action of cross-currents. When a pulse istransmitted from transducer members 22, it is radiated essentiallynormal to the direction of body 10, or horizontally. Reflections fromunderwater objects will be returned and sensed at the surface of member16 at the various staves which respond to these echo signals at the timethey are received. This time relationship means that a given echo signalhaving a particular direction will arrive at adjacent staves at slightlydifferent times or, stated differently, in slightly different phaserelationship. This phase relationship is used in the electronic packageto determine the bearing of the reflecting object. With this hearinginformation and with synchronized means for determining the elapsed timebetween the transmitted pulse and the reception of the echo, bothbearing and range can be determined and transmitted through the cable 12to be displayed on a cathode ray tube in the associated vehicle.Obviously, the specific functions ascribed to the electronic package 20are typical only and do not form a part of the present invention sinceall or part of the signal-processing functions described may be locatedin auxiliary equipment at the opposite end of cable 12. a

Removal from the water is effected by winding in cable 12, and again itis desirable that the orientation of the transducer remain as close tovertical as possible with a minimum of turbulence and non-axial movementwhich would load the hoisting mechanism and slow the rate of ascent.Even with the configuration-shown, the transducer had some tendency tonutate with the nose section moving in a-circle on ascent until the fins32 were'added. These provided sufiicient resistance vto lateral movementthat ascent through the water remained essentially straight andvertical.

While only one embodiment hasbeen shown and described herein,modifications within the spirit and scope 4 of the present invention maybe made to suit particular requirements. While body 10 has'been'shownas-essentially cylindrical, it could be made with a somewhat largerdiameter toward the lower end which would permit larger transmittingelements, if needed, at some cost in resistance to flow through thewater so long as the contours permit smooth flow with a minimum ofturbulence. Similarly the diameter of member 16 may be varied withinlimits to accommodate greater or lesser numbers of staves depending onthe resolution required of the transducer. The fins 32 may be of avariety of sizes and shapes so long as enough area is present to providethe required lateral stability. More than two oppositely directed finsmust, be used to provide stability in more than one plane. Othermodifications will occur to those skilled in the art, and I do not wishto be limited to the particular configuration shown or otherwise than bythe appended claims.

We claim: I

1. A transducer for connection to cabling means and adapted to beoperated at substantial depths comprising a smooth elongated bodyconnected at its upper end to said cabling means and substantiallycircular in crosssection;

a plurality of support members extending radially from said-body; I

a hollow cylindrical member attached to the outside ends of said supportmembers and spaced from said body to permit water to flow between saidbody and said member, said cylindrical member containing a plurality oftransducer elements electrically connected in groups such that eachgroup responds to received acoustic signals as an individual unit;

a plurality of transmitting transducer elements located in said body,and an acoustically transparent sleeve member containing saidtransmitting elements;

electronic amplification and signal-processing means in said bodyconnectedto said transducer elements; and

a plurality of fins extending radially from said body near the oppositeend from said cabling means, said electronic means, said transmittingtransducer elements and said cylindrical member being arranged relativeto said body such that the center of gravity of said transducer islocated a substantial distance below said cylindrical member.

2. A transducer as set forth in claim 1 wherein said body is generallystreamlined in configuration to aid in rapid descent into the water andremoval from the water.

3. A transducer as set forth in claim 1 wherein the weights of the partsare such that the center of gravity is nearest the end of said bodycarrying said fins.

4. A transducer as set forth in claim 3 wherein additional weight isadded to aid in rapid descent into the water.

5. A transducer as set forth in claim 1 wherein a center post structureis located within said transmitting elements to serve as a structuralmember and also as an acoustic tuning means. a

6. A transducer as set forth in claim 1 Whereinsaid groups of receivingtransducer elements are physically arranged as a plurality of groupsaligned axially with respect to said elongatedbody.

7.-A transducer as set forth in claim 1 wherein said support means areattached near the upper end of said body and said transmittingtransducer elements are lo-' cated near the lower end of said body.

8. A transducer for connection to cabling means and adapted to beoperated in water at substantial depths comprising a smooth elongatedbody substantially circular in cross-section having a length severaltimes greater than its diameter;. v V

a plurality of hollow support members extending radially from the end ofsaid body nearest said cabling means; a hollow cylindrical member ofsubstantially greater diameter than said body member attached to theoutside ends of said support members, said cylindrical member containinga plurality of transducer elements arranged and electrically connectedin axial groups such that each group responds to received acousticsignals as an individual unit;

a plurality of transmitting transducer elements located in said bodynear the opposite end from said cylindrical member and acousticallytransparent means surrounding said transmitting elements;

electronic amplification and signal-processing means in said bodyconnected to said transducer elements; and

'a plurality of fins extending radially from said body at the oppositeend from said cylindrical member.

References Cited UNITED STATES PATENTS Schurman 340-17 Lang 114-20Sampsell 340-9 X Lei-boWitz et a1 340-9 X Tullos 340-8 Green 340-8Martin et a1. 340-8 BENJAMIN A. BORCHELT, Primary Examiner. P. A.SHANLEY, R. M. SKOLNIK,

Assistant Examiners.

